I getting ready to rebuild my block(it old and the leak down test is showing it) but I picked up a vortec supercharger for my car (jdm GSR in a civic) Now I figure while I have the it apart I might as well get a new set of pistons for it.. I have to run on 91 octane, and I know I could make more HP with a turbo, but I am not interested in one.. So what compression ratio should I get to make the most HP/TQ on 91 octane pump gas in a b18c with a vortec supercharger on it..... Locashracing will be tuning it with my hondata s200 setup....

Thanks in advance

 

9:1 Compression Ratio is most common in forced induction motors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B00STFREAK &raquo;</TD></TR><TR><TD CLASS="quote">9:1 Compression Ratio is most common in forced induction motors.</TD></TR></TABLE> I understand that, but from what i understand 9:1 c/r is for people looking to expand their boost... I'm only looking to hook up a vortec supercharger with either an 8lbs pulley or maybe a 10 lbs pulley..Now if I was going turbo'd I would be doing something like that maybe even 8.8:1

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92 civic VX B18c &raquo;</TD></TR><TR><TD CLASS="quote"> I understand that, but from what i understand 9:1 c/r is for people looking to expand their boost... I'm only looking to hook up a vortec supercharger with either an 8lbs pulley or maybe a 10 lbs pulley..Now if I was going turbo'd I would be doing something like that maybe even 8.8:1</TD></TR></TABLE>

You can do 11:1 if you wanted.
But im just saying that 9:1 is more practical for the application IMO.

 

with my motor, i am supposebly running 9.96:1, i run 15 psi. For your boost levels, i'd just stay stock personally. You should search though, its been discussed on here plenty of times. If anything buy new pistons for the forged aspect of it.

 

at that boost, your stock C/R is fine, hell your stock motor is fine!

Merry Christmas

 

I would keep it stock cr as well.

 

stock cr

 

Go 9:1 because eventually you will realize you want a turbo instead

 

Right now I am @ 10.9-11.1:1 compression, my tuners says it's doable My stock compression is 10.6:1

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">Go 9:1 because eventually you will realize you want a turbo instead </TD></TR></TABLE> Actually I've thought long and hard about this car and turbo is not the route i would like to go with it... Although I have been planning togo turbo on my LS1 powered 1972 Nova

 

Detonation is a LOT easier at 11:1 than 9:1. I've also seen a bunch of dyno plots showing a just a few more HP before the turbo spools, a slightly earlier spool, and more power overall.

If you want all that, I'd have to say use a bigger bore instead. I'd rather loose a bit of gas milage than end up with pitted pistons or cracked sleeves (worst-case).

 

I swear noone is replying to my question, for some reason I think HiProfile thinkks I am talking about a turbo
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HiProfile &raquo;</TD></TR><TR><TD CLASS="quote">Detonation is a LOT easier at 11:1 than 9:1. I've also seen a bunch of dyno plots showing a just a few more HP before the turbo spools, a slightly earlier spool, and more power overall.
</TD></TR></TABLE>

Let me straighten a few things out

1. I know I could make more HP with s turbo set up

2. I already own the supercharger but I have not installed it yet

3. I am replacing my piston because my compression tests shows I need a rebuild

4. I will be using this as a Daily Driver with a commute of 40 miles each way to and from work 6 days a week or more..

5. I know 9.1:1 is a good starting place and would leave me room to expand..

6. What compression ratio would be Ideal/optimum for pushing(making it easy) 8psi using a vortec supercharger?

7. Car with be tuned with Hondata s200(already installed 195whp/142ft/lbs of tq N/A

 

keep it stock and throw a slightly thicker cometic headgasket on there to lower c/r and youll be fine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2k.civic.si &raquo;</TD></TR><TR><TD CLASS="quote">keep it stock and throw a slightly thicker cometic headgasket on there to low c/r and youll be fine </TD></TR></TABLE> I guess I need to clear up another thing..

My engine
JDM b18c(GSR 10.6:1 compression)
Endyn ported Head
Skunk2 High Compression Valves
Toda Springs and Retainers
Skunk2 Stage2 cams
Skunk2 intake manifold
Edlebrock 68mm TB
RC 310cc Injectors
RMF Header
Fluidyne Radiator
Hondata S200

 

well hell...if you have that kinda money get forged rods and pistons...i would pick 9:1 c/r at that point...in a boosted app the c/r under boost makes very little difference...plus it allows for more boost later on...and with the vortec kit i would push more like 12psi

 

2k.civic.si thanks for the reply

So in a boosted engine the compression ratio makes little differance to the horsepower & torque output of the engine? hmm thats something for me to think about and research

 

if you have the motor apart i would put forged rods in it as well. as far as a compression ratio you will be fine anywhere from 9:1-10:1 it all depends on whether or not you plan on raising the boost later on(which you will) so i would suggest getting the 9:1 compression pistons(your c/r will be slightly higher with those pistons than 9:1 since you have high comp valves and the head has probably been resurfaced once and will probably need it again) the lower the compression the harder it is for the engine to detonate on a good tune.

hope it helps